The present invention relates generally to improvements in cleaning devices in electrophotgraphic copying machines, electronic printers and similar machines employing a toner for forming copy images and it relates more particularly to an improved cleaning device for removing deposited toner and other residue from a moving surface such as the periphery of a toner fixing roller and the like.
In electrophotographic copying and similar machines wherein an image is formed of a particulate finely divided toner, the toner image is commonly fixed or fused to a substrate by fixing rollers. Some of the toner and frequently other residues are generally deposited on a rotating roller and unless such deposited toner and residue is removed, a deterioration in the quality of the copy and other undesirable results occur. Cleaning devices for removing the deposited toner and residue include a cleaning member which is usually disposed in contact with the surface of the fixing roller. Commonly used as such a cleaning member is a cleaning roller having an outer peripheral surface formed of metal, rubber, felt or the like (as described, for example, in U.S. Pat. No. 3,649,992 and U.S. Pat. No. 3,868,744), or a cleaning blade made of metal, rubber, film or the like (as described, for example, in U.S. Pat. No. 3,986,227).
However, the cleaning members heretofore employed and proposed possess numerous drawbacks and disadvantages.
The former cleaning member, that is, the cleaning roller, must be very frequently cleaned to remove toner therefrom or must be frequently replaced. Further, to achieve an improved cleaning efficiency, the cleaning roller must be rotated in a direction opposite to, or in the same direction as the direction of rotation of the fixing roller, with a difference between the peripheral speeds of the two rollers at the nip thereof. This entails the drawback that a drive transmission must be additionally provided. With the latter cleaning member, that is the cleaning blade, there is the requirement that the blade be held in uniform contact with the fixing roller, so that the blade, when made of metal, causes damage or wear to the fixing roller, particularly so if the roller is covered with an elastic member over its outer periphery. There is the further drawback that agglomerates of toner particles cause damage to the fixing roller at the contact portion.
Besides the above devices, another cleaning device is known in which a cleaning member is wound up by a small amount at a time to always position a clean portion in pressing contact with the fixing roller. This device, however, possesses the drawback of being complex in construction and requiring a large space.